ARM: defconfig: turn on the DT cpufreq for Integrator

The Integrators are now migrated to handle the CPUfreq
scaling using the generic devicetree CPUfreq driver using the
common clock framework and have the required device tree
modifications, so turn off the old driver and turn on the new
generic driver.

Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>